Review of LIGO Upgrade Plans

Yuta MichimuraDepartment of Physics, University of Tokyo

April 13, 2017Ando Lab Seminar

• Introduction

• A+

• Voyager

• Cosmic Explorer

• Other issues on ISC

• Summary

• KAGRA+

Contents

2

• J. Miller +, PRD 91, 062005 (2015)

Prospects for doubling the range of Advanced LIGO

• B. Shapiro +, Cryogenics 81, 83 (2017)

Cryogenically cooled ultra low vibration silicon mirrors for

gravitational wave observatories

• B P Abbott +, CQG 34, 044001 (2017)

Exploring the sensitivity of next generation gravitational

wave detectors

• LSC, LIGO-T1500290

Instrument Science White Paper 2015

• LSC, LIGO-T1600119

The LSC-Virgo White Paper on Instrument Science (2016-

2017 edition)

References

3

GW Detectors in the World

4

USA Europe Japan

1G

2G

3G

LIGO(2002-2007)

Enhanced LIGO(2009-2010)

Advanced LIGO(2015-)

A+(2017?-)

Voyager(2025?-)

Cosmic Explorer(2035?-)

TAMA(1999-2004)

KAGRA(2020?-)

Virgo(2007-2011)

Advanced Virgo(2017?-)

Einstein Telescope(2030?-)

GEO(2002-2009)

GEO-HF(2009-)

KAGRA+(2024??-)

GW Detectors in the World

5

LIGO(2002-2007)

Enhanced LIGO(2009-2010)

Advanced LIGO(2015-)

A+(2017?-)

Voyager(2025?-)

Cosmic Explorer(2035?-)

TAMA(1999-2004)

KAGRA(2020?-)

Virgo(2007-2011)

Advanced Virgo(2017?-)

Einstein Telescope(2030?-)

GEO(2002-2009)

GEO-HF(2009-)

KAGRA+(2024??-)

USA Europe Japan

1G

2G

3G

Advanced LIGO Noise Budget

6LIGO-T1600119

• Ground motion

• Reduction method

- longer arms

- low frequency suspension

- multiple stage suspension

- site selection (underground, less human activities)

Seismic Noise

7

http://www.kinki-geo.co.jp/joujibidou.pdf

• Brownian motion of fibers

• Reduction method

- longer arms

- high Q material

- longer and thinner fiber

- cryogenic temperature

Suspension Thermal Noise

8

http://gwwiki.icrr.u-tokyo.ac.jp/JGWwiki/KAGRA

• Brownian motion of mirror surface coating

• Thermo-optic noise

- Thermo-refractive noise

thermal change in the refractive

index of the coating

- Thermo-elastic noise

thermal expansion of the coating

• Reduction method

- longer arms

- high Q material

- cryogenic temperature

- larger beam size

Coating Thermal Noise

9

Ta2O5

Ta2O5

Ta2O5

Ta2O5

SiO2

SiO2

SiO2

SiO2

interference

mirror substrate

• Quantum fluctuation of light

Radiation pressure noise Shot noise

• Reduction method

- longer arms

- interferometer configuration

(higher finesse, RSE, etc.)

- heavier mirrors

- squeezing

Quantum Noise

10

mirrorphotodiode

Laser

• Longer arms

Seismic, Suspension thermal, Coating thermal, Quantum

• Better suspension

Seismic

• Underground

Seismic

• Lager mirror (allows larger beam size)

Suspension thermal, Coating thermal, Quantum

• High Q material

Suspension thermal, Coating thermal

• Cryogenic temperature

Suspension thermal, Coating thermal

• Squeezing

Quantum

Summary of Noise Reduction

11

Estimated LIGO Timeline

12

LIGO-T1600119

Estimated LIGO Timeline

13

LIGO-T1600119

• Modest cost upgrade of aLIGO (< $10M-20M)

• Factor of 2 improvement in sensitivity

quantum noise

coating thermal noise

• Two stages

- frequency dependent squeezing

(after O2, 2017)

- better coating, possibly low-risk changes to suspensions

(after O3, 2018-2019)

• Also as risk reduction for aLIGO

- squeezing in case high power is difficult

- improved coating in case coating thermal noise is

underestimated

• Heavier mass, improved suspension for lower thermal noise

-> little impact on the astrophysical output

Advanced LIGO+ (A+)

14

reduce gas damping,

improve bounce and roll damping,

mitigate parametric instabilities, etc.

• Frequency dependent squeezing with 16m long filter cavity

(4km filter cavity is not required if no change in other noises)

• Coating thermal noise

AlGaAs crystalline coating not demonstrated with

40cm-scale mirror

• Heavier mass not feasible

400kg and 1m diameter fused silica possible

Polishing with Ion Beam Figuring up to 50cm possible

Coating up to 40cm possible (CSIRO),

LMA planning to scale-up

• Suspension thermal noise -> little impact

longer fiber, higher stress

heat treatment of fibers to reduce surface losses

modify geometry

A+ Details

15

• Benefit of each improvement assuming all other

improvements (6 dB) have already been made

Relative importance of upgrades

16

Quantum and Coating thermal

have largest effect up to 6 dB

4km filter cavity is effective

when other noises are reduced

Suspension thermal

have small impact

LIGO-T1600119

• 16 m filter cavity, 6 dB measured squeezing, 1/2 loss in

coating high refractive index layer

A+ Nominal Noise Budget

17LIGO-T1600119

• 4 km filter cavity, 8 dB measured squeezing, 1/4 loss in

coating high refractive index layer

A+ Optimistic Noise Budget

18LIGO-T1600119

• Mode matching, alignment control (OMC, filter cavity,

squeezed light source)

• Newtonian noise subtraction

• Better ISI (Internal Seismic Isolation)

improved vertical inertial sensor, improved position sensors

to reduce RMS motion of ISI

• Stray light control

• Arm length stabilization system

reduce complexity (possibly inject green from vertex)

• Optical coating quality

to reduce scattering

• Charge mitigation

• PSL design to minimize noise couplings

• Larger BS

Other R&Ds

19

• K. Goda+, Nature Physics 4, 472 (2008)

Squeezing with prototype SRMI

• LSC, Nature Physics 7, 962 (2011)

Squeezing with GEO600

• J. Aasi+, Nature Photonics 7, 613 (2013)

Squeezing with LHO

• E. Oelker+, PRL 116, 041102 (2016)

2 m filter cavity at 1.2 kHz

• A. R. Wade+, Scientific Reports 5, 18052 (2015)

• E. Oelker+, Optica 7, 682 (2017)

~1mrad phase noise with OPO

under high vacuum

• 16 m filter cavity prototype

at MIT on going

Experimental Demonstrations

20

Estimated LIGO Timeline

21

LIGO-T1600119

• Major upgrade within existing facility

• Factor of 3 increase in BNS range (~1100Mpc)

• 200 kg Silicon, 123 K

• 200 W laser at 2 um

wavelength could be 1.55-2.1 um- silicon absorption

- stable high power laser

- quantum efficiency of PDs for squeezing

(high for 1064 and 1550 nm)

- wide angle scatter loss 1/λ2

• Shin-Etsu will make 45 cm dia. mCZ

(magnetic field applied Czochralski)

• amorphous Si/SiO2 coating

• see LIGO-T1400226

Voyager

22R. X. Adhikari, GWADW2017

• 300m filter cavity, 10 dB squeezing

Voyager Noise Budget

23LIGO-T1600119

worse than A+ ?

• 123 K for zero thermal expansion

thermoelastic noise, minimize RoC change

• Radiative cooling (no conductive heat path needed)

5 W heat extraction

• Movable heat link for initial cool down

Cryogenic Layout

24B. Shapiro +, Cryogenics 81, 83 (2017) & LIGO-T1400226

• Demonstrated

low temperature

and

low vibration

can be realized

Stanford Experiment

25B. Shapiro +, Cryogenics 81, 83 (2017)

• Mirror reached 121 K

Stanford Experiment

26B. Shapiro +, Cryogenics 81, 83 (2017) Liquid nitrogen ran out

• Inner shield displacement meets

the requirement (from scattering)

Stanford Experiment

27B. Shapiro +, Cryogenics 81, 83 (2017)

• Cryogenic system is not impacting the vibration isolation of

the mirror

Stanford Experiment

28B. Shapiro +, Cryogenics 81, 83 (2017)

Displacement of

vibration isolation table

Estimated LIGO Timeline

29

LIGO-T1600119

• New facility

• BNS range beyond z=1 (~4 Gpc)

• Adapt A+ and Voyager technology to much longer arms

• Or, shorter baseline designs with breakthroughs in

- Newtonian noise cancellation

- coating and mechanical system engineering

- quantum non demolition interferometry

• Long life time (~50 years)

• On the surface or underground

1-10 Hz sensitivity in terms of

science/dollar

• L-shape or triangular shape

polarizations

Cosmic Explorer

30

• Quantum noise (fixed cavity pole)

• Coating thermal noise (fixed cavity geometry; w∝L)

• Suspension thermal noise and seismic noise

vertical noise coupling linearly increases with length

(due to the curvature of the Earth)

Longer Arms

31

Coating thickness and beam size grow with wavelength but the effects cancel

Hidden dependence: longer arms require larger mass because of larger beam

B P Abbott +, CQG 34, 044001 (2017)

• From Hongo Campus to Hachioji

40 km

32

• Based on Voyager technology (Silicon, 123 K, 1550 um)

CE Optimistic Noise Budget

33LIGO-T1600119

• Based on A+ technology, conservative coating improvement

CE Pessimistic Noise Budget

34LIGO-T1600119

• Essentially all compact binary coalescence in the universe

for z>20 mass range

Astrophysical Reach

35LIGO-T1600119

• Vibration noise from heat links

suspension point interferometer ?

• Improve robustness of the arm length stabilization system

inject green from vertex ?

• High power photo-detection

• Mode matching of output mode-cleaner (OMC)

interferometer thermal state

• Balanced homodyne detection for DARM

to allow for tunable homodyne readout angle

to avoid technical noises

• Sidles-Sigg instability

potential threat for Voyager/CE since higher power

angular control noise reduction ?

optical trapping of alignment ?

Other Issues (= Chances) on ISC 1

36

LIGO-T1600119

• Alignment sensing and control

OMC, squeezed light source, filter cavities ……

higher power, more higher order modes

band of GW detection moves down, but bandwidth

of alignment control increases (Sidles-Sigg)

• Thermal aberration sensing and control

modeling, wavefront sensors

• Fast data acquisition (increase sampling frequency)

• Adaptive noise cancellation, automatic optimization, modern

control

• Virtual interferometer (Simulated Plant)

• Mechanical simulation tool for vibration isolation system

automatically compute thermal noise

• Modelling thermal distortions and radiation pressure

Other Issues (= Chances) on ISC 2

37

LIGO-T1600119

Summary

38

• Integrated realistic studies, R&D experiments are ongoing

for LIGO upgradesLIGO-T1600119

(may be not scientifically exciting itself,

but necessary for big science)

Summary

39

• Integrated realistic studies, R&D experiments are ongoing

for LIGO upgradesLIGO-T1600119

KAGRA

3

23

Sapphire

23 K

23 K

35 cm Sap.

Fiber

55

290

1064

1

3.5 / 3.5

0

none

(may be not scientifically exciting itself,

but necessary for big science)

Summary

40

• Integrated realistic studies, R&D experiments are ongoing

for LIGO upgradesLIGO-T1600119

KAGRA

3

23

Sapphire

23 K

23 K

35 cm Sap.

Fiber

55

290

1064

1

3.5 / 3.5

0

none

(may be not scientifically exciting itself,

but necessary for big science)

• We should plan ahead (~10 years)

• Some R&D ongoing, but needs integrated study

- 300 m filter cavity experiment at NAOJ

- coating thermal noise experiment at NAOJ

- mirror absorption measurement at NAOJ

• Heat extraction vs suspension thermal noise

- thick short suspension is better for heat extraction

- thin long suspension is better for thermal noise

- lower the power ?

- less absorption ?

- half cryogenic ?

- 123 K ?

- ribbon ?

KAGRA+?

41http://gwwiki.icrr.u-tokyo.ac.jp/JGWwiki/KAGRA

Ribbon Suspension

42

E. Nishida, JGW-G1100558 (2011)

R. DeSalvo, JGW-G1201101 (2012)

whr

• Keep cross section

to keep heat extraction,

but move violin modes

to higher frequency

Sapphire vs Silicon

43

Yoichi Aso, JGW-G1000113 (slide from LCGT f2f meeting 2010)

• Gravitational-wave Advanced Sapphire Technology

GAST Proposal by LMA et al

44G. Cagnoli, 8th ET

Symposium (2017)

• Underground facility and serious cryogenic system (20 K)

are futuristic attractive infrastructure

• Filter cavity seems feasible, but adds more complexity

(alignment, mode matching, etc.)

• Heavier mass + frequency independent squeezing +

low power + cryogenic + underground

sounds simple for me

• Could be sapphire,

could be silicon

• R&D facility for heavier mass

cryogenic suspension,

mirror polish, coating ?

• Silicon prototype

interferometer ?

Random Thoughts

45